An email has been sent to ticket holders stating that the start date would be "delayed indefinitely" at the Holywell location until issues have been resolved with the land surrounding the ship and the required work completed.

Ticket holders have been advised to rebook at a different location, or to contact the organisers for a refund.

Concerns were raised by the emergency services about access to the vessel, which has been docked at Llanerch-y-Mor for over 30 years.

The Duke of Lancaster has been docked for more than 30 years (Image: Berit Watkin)

The only access available is via Glan-y-Don railway bridge, which has a weight restriction of 10 tonnes according to signage.

Fire safety chiefs are asking organisers for confirmation that the bridge is strong enough to bear the load of a fire appliance, which weighs in the region of 12 to 14 tonnes.

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A number of large pot holes along Cob road, which leads to the bridge, are also believed to be an issue for the emergency services and unsuitable for their appliances.

It is understood the capacity of the bridge was discussed by engineers and the Network Rail Route Structures team, who confirmed in 2014 that the actual weight limit for the bridge is 40 tonnes.

There are concerns that the bridge used to access the ship would not be strong enough to carry fire appliances

In a statement on social media, a spokesperson for the Duke of Lancaster appreciation group said: "All the events have been cancelled for the time being.

"The zombie people (Zombie Infection Events) had a meeting with North Wales Fire and Rescue who once again required confirmation that the bridge is strong enough to carry their appliances as it has been 4 years since the last confirmation.

"They also requested the load bearing capacity of the Cob Road and the need for the pot holes to be filled in, but we couldn't gain permission to do so.